Electro-mechanical means for reversing direct current



4 Sheets-Sheet 1 J. A` POLLAK ELECTRO-MECHANICAL MEANS FOR REVERSING DIRECT CURRENT Filed Jan. 2J., 1963 Aug. 10, 1965 Aug. 10, 1965 J. A. POLLAK 3,200,219

ELECTRO-MECHANICAL MEANS FOR REVERSING DIRECT CURRENT Filed Jan. 2J., 1963 4 Sheets-Sheet 2 INVENTOR. ma f ATTORNEYS Aug. l0, 1965 J. A. PoLLAK 3,200,219

ELECTRO-MECHANICAL MEANS FOR REVERSING DIRECT CURRENT Filed Jan. 2J., 1963 4 Sheets-Sheet 5 INVENTOR. ./o/wv A. POLLQK afa WM Aug. 10, 1965 J. A. POLLAK 3,200,219

ELECTRO-MECHANICAL MEANS FOR REVERSING DIRECT CURRENT Filed Jan. 2J., 1963 4 Sheets-Sheet 4 INVENTOR.

JOHN ,9. Ponen/f M12/m@ n @lf-5v ATTOR/Vfys? United States Patent O 3,2titl,219 ELEfCi'RtB-MECHANICAL NEANS EUR REVERSEING DHRECT CURRENT .lohn A. Poilak, Detroit, Mich., assigner to Aliied Research Products, incorporated, Baltimore, Md., a corporation f of Maryland Y Filed llan. 21, 1963, Ser. No. 252,959

17 Claims. (Cl. 26o-98) This invention relates to a current reversing unit and more particularly to an electro-mechanical device for periodically reversing a DC. current.

In many electro-chemical processes, for example, in electrolytic cleaning and in copper plating, it is desirable and sometimes necessary to reverse the current so that during one interval of time the workpiece being treated within .a tank is anodic and during a successive linterval of time the workpiece is cathodic. To accomplish this periodic reversal in polarity, relays have been conventionially used in the past. The use of relays for periodically reversing the polarity of DC. current in the electrochemical eld has certain disadvantages. When it is considered that it is not unusual to employ currents as high as 3,000 amperes, the use of commercial relays, usually designed to operate at Ia maximum current of 50 amperes, is obviously undesirable because of the numerous relays that have to rbe employed. Furthermore, relays burn out lfrequently and this further adds to the disadvantages of using relay type current reversing devices.

`lt is an object of the present invention to provide an electro-mechanical device for periodically reversing the current to a pair of terminals connected to a source `of direct current.

A further object of the invention resides in the provision of a current reversing unit which is of economical construction Aand which -is adapted to carry very high currents without presenting any problem of overload.

In the drawings:

IFIG. 1 is a side elevational view, partly in section, of the current reversing uni-t of my invention.

FIG. 2 is an end View, partly broken away and partly in section, of the current reversing unit of this invention.

FIG. 3 is a top plan View of the unit.

FIG. 4 is a sectional view :along the line 4 4 in FIG. l.

lFIG. 5 isa block diagram showing in a general way the manner in which the current reversing unit of this invention is oper-ated. v

The current reversing unit of the present invention includes a housing that can be economically construoted of .angle iron to form generally rectangularly shaped top and bottom fra-mes 12 and 14, respectively, which are interconnected at their ends by upright angles 16 and 1S and .at the center portion of each side thereof by intermediate upright angles Ztl. At each side of housing 10, there is mounted, as by screws 22, a pair of platelike supports 24 ea-ch formed with a semi-cylindrical opening 26. Supports 24 .are formed of an electrical insulating material such as Bakelite. A pair of high purity copper cylindrical tubes 28 extend crosswise of struct-ure 12 and are mounted on supports 24 by screws 30. The tubes 2S are seated at each end inthe downwardly facing semicircular seats 26 in supports 24.

At ea-ch end, housing 10 is provided with an end panel 32 which is formed of j an electrical insulating material such as Bakelite. T-he input and output terminals extend through these end panels. rThe two input terminalsrare designated 34 and 36, respectively, and the two output terminals are designated 38 and 4d, respectively. EachA input terminal comprises a pair of bus bars secured together face to face and supported on their respective end panels 32 by angle brackets 42 (FIGS. l and 4). To the inner end of each input bus bar 34, 36, there is bolted as at 44 .a right .angle connecting bar 46 which is likewise formed of two pieces of copper secured together in faceto-face rel-ation. The lower horizontal leg of connecting bar 46 has bolted thereto as vat 48 a tube clamp S0. Each tube clamp 50, as is shown in FIG. l, has an arcuate portion which overlies the outer top surface of its respective tube 23 and is secured thereto in intimate electrical conducting relation by screws 52. The output terminals 38, 40 are supported adjacent their outer ends on the end panels 32 by mounting angles 54. The inner ends of terminals 33 and 40 are supported on an insulating cross bracket 56 by angles 53. Cross bracket 56 is supported at each end on the intermediate upright angles 20.

Adjacent the intermediate upright :angles 20, there is mounted on bot-tom frame 14 a pair of cross bars 60 formed of an insulating material such as Bakelite. On the top side of each cross bar 6), there are mounted as by screws 62 two Bakelite supports 64, one adjacent each side of housing 10 as shown in FIGS. 3 and 4. Each support 64 has pivotally connected thereto a contact shoe. These shoes are formed as copper castings and are designated 66, 68, and 72. The pivotal connection between each support 64 and its cont-act shoe includes a hardened steel pin 74 on the Contact shoe which is journalled in a hardened steel bus-hing 7 6 in the support 64. Each contact shoe is fashioned with a relatively wide arcuate contact `face 78 which is lapped to the exact contour of the .surface portion of the tube 28 with which it is adapted to engage. The contact face 73 of each shoe is cast integrally with a pair of ribs 80, the free ends of which are pivotally connected as at 82 with the lower end of a link d4.

yDirectly above each contact shoe, there is supported on top frame 12 an operating solenoid for the shoe. The solenoids are designated 86, 38, 90, 92. Solenoids are secured to cross angles 94 on top frame 12 by screws 96. The movable plunger 98 of each solenoid has a pair of support brackets 109 pivotally suspended therefrom. An insulating block 1412 is mounted as by screws 194 on the inturned ends 106 of support brackets 1%. A screw 108 extends downwardly through a hole in insulating block 102 and is threaded as at 110 into the upper end of link 84. Between thetop side of insulating block 102 and the head of screw 168, there is arranged a coil spring 112. When a solenoid is energized, its plunger 9S is pulled upwardly, thus raising link 84 and pivoting the respective shoe int-o contact with the tube 28. Springs 112 form a yieldable connection between each solenoid and its contact shoe to accommodate for wear and assure perfect c-ontact between the contact surface 78 of each shoe and the adjacent 'surface portion of the tube 28 with which it is associated.

Each contact shoe is fashioned with a terminal lug portion 114 to which an electric cable is adapted to be connected. Four such cables are provided. These are designated 116, 118, and 122. Cable 116 extends from output bus bar 3S as at 124 to shoe dit. Cable 118 extends from bus bar 3S to shoe 7d. Cable 12b` extends from output bus bar 4t) as at 125 to shoe 68 and cable 122 extends from bus bar 4d to shoe 72. These cables are ilexible and are connected to their respective shoes by screws 12S.

As is illustrated in the block diagram of FIG. 5, in operation, the input terminals 34, 36 of the current reversing unit of this invention are connected to the output side of a rectifier which is in turn connected to a source of alternating current as indicated at 132. The output terminals 33, 46 of the current reversing unit are connected to a plating tank in a conventional manner. For the purpose of energizing solenoids 36, 88, 90, 92, a timer 134 is employed. Timer 134 may be of any conventional type, its purpose being merely to energize and heating.

the solenoids so as to eliminate arcing between the con-v tact shoes and the tubes 2.8. Timers for alternately energizing and de-energizing solenoids in this manner are commercially available and further description of timer 13d is therefore unnecessary.

' The alternate closing of the two sets of contact shoes by energizing'and de-energizing their operating solenoids reverses the polarity at the output bus bars 33, ftd. For example, when solenoids S3 and 90 are energimd'andV assuming that bus bar 34 is positive and busbar Y3d is negative, then the positive ycurrent flows from bus bar 3ft through its clamp 5@ to tube Z2 through the contact shoe o8 and cable i2@ to the 4output bus bar 4t) which is thus positive. The negative current tlows from input bus bar 36 through its clamp 5d to the other tube 2S and then through contact shoe 7@ and cable H8 to the output vbus bar 33 which is thus negative. When timer i3d de-l energizes solenoids 38, @d and energizes solenoids 86, 92, contact shoes 63, 'it break with tube 23 and contact shoes 6d, '72 are pulled up into contact with their respective tubes 28. Thus, the positive current from bus bar 34 now iows through the tube 2S through shoe d6 and through cable il@ to bus bar 33 which thus becomes positive and the negative currentV from bus bar 36 flows through the other tube 28 through contact shoeV '72. and cable E22 to bus bar fill which thus becomes negative.- n

, i have thus provided an electromechanical device for periodically reversing the polarity of a DC. current which is of economical construction, reliable in operation and adapted to carry very high currents without the Vdanger of overload. The contact shoes provide a` large v area of contact with the tubes 28. When it is considered that Vabout one square inch of copper Contact area can safely carry about 1,000 amperes, it will be realized that each contact shoe can carry 3,600 or more amperes without any difficulty. VThe current carrying capacity of the contact shoes can he further increased by forced air cooling of the shoes and the copper tubes Z8. This is one advantage of forming the conductors Z8 as tubes. They not only provide a maximumcurrent area for a given space but radiate heat rapidly and are easily adapted for forced air cooling so as to Veliminate the problem of over- Furtherrnore, by lapping the curved contact surface '78 of each shoe to the exact Vcontour of the portion of the copper tube` which it contacts, a nearly perfect and total contact area is obtained. In addition, the

' use of the yielding connection between each solenoid and its Contact shoe through the provision of slring H2 accommodates for wear in the contact shoes and tubes and also eliminates the need for accurate adjustment of the closed length of the solenoid links 84. Iclaim: Y

1. A device for periodically reversing the polarity of a D.C. current comprising a pair of input terminals adapted to be connected to a source of DC. current, a pair of youtput terminals, a pair of cylindrical conductors, one of said pair of terminals being electrically connected to said cylindrical conductors, a plurality of four contact shoes, one pair of said contact shoes being arranged when actuated to circumferentially engage and make'con- `tact with the cylindrical surface of one of said cylinminals and means for periodically and alternately closing one contact shoe in each pair and then the other contact shoe in each pair with their respective cylindrical conductors. Y

2; A device as called for in claim l wherein said last mentioned means includes solenoids, the movable members of which are operatively connected with said contact shoes.

3. VA -device as called for in claim 2 wherein said shoes are formed with a contact surface defining a segment of a cylinder corresponding to the outer cylindrical surface of the cylindrical conductors, said solenoids being adapted to shift said contact shoesv to a position such that the contact surface of the shoesV intimately engages the outer cylindrical surface of said cylindrical conductors.

4. A device as called for in claim 2 wherein said shoes Vare pivotally supported.

5. A device as called for in claim 2 wherein the operative connection between the movable elements of the solenoids and said shoes includes a resiliently yieldable member. 1

6. AY device for periodically reversing the polarity of a LDC. current comprising a pair of input terminals adapted to be connected to a source of D.C. current, a pair of output terminals, a pair of conductors, each having a pair of broad, relatively large contact faces, one of said pair of terminals being electrically connected with said conductors, a iirst pair of contact members each movable to make with said two conductors, said contact members being connected with one of the terminals in the other pair of terminals, a second pair of contact members each movable to make with the two conductors, said contact members also having broad, relatively large contact faces movable into close face to face engagement with the contact faces of the conductors, said second pair of contact members being connected with the other terminal of said other pair Vof terminals, a plurality of four solenoids pivotally connected one with each contact member for operating the contact members and means for periodically and alternately energizing said solenoids in pairs for alternately n moving eachpair ofY said contact members to the make position.

7. An electro-mechanical current reversing unit comprising a support, a pair of electrically conducting tubular members on saidsupport, a first pair of contact shoes pivotally mounted on said support and adapted to pivot Vinto and out of contact one with each of said tubular members, ay second pair of contact shoes pivotally mounted on said support and adapted to pivot into and out of engagement one with each of said tubular members, a pair of input terminals connectd one with each of said tubular members, said input terminals being adapted to be connected to a source of direct current, a pair of output terminals, the contact members in one of said pairs being connected to one output terminal and the contact members vin the other pair being connected to the other output terminal whereby the alternate closing of saidtwo pairs of contacts reverses the polarity at said output terminals. f

Y 8. A current reversing unit as called for in claim 7 wherein said tubular membersy have a cylindrical Vouter surface and said shoes are formed' with an arcuate contactsurface defining a cylindrical segment, said contact surface of each shoe conforming to the outercylindrical surface of said tubular members and being adapted for intimate engagement therewith throughout a substantially dricalconductors and the other pair of contact shoes bcing'arran'ged when actuated to circumferentially engage and make Contact with the cylindrical surface of the other cylindrical conductor, onecontact shoe in each pair being connected to one of the terminals in the other pairof Y terminals and the other contact shoe in each pair being connected Vto the other terminal in said other pair of terlarge area,

9. A current reversing unit as` called for in claim 8` including solenoids for pivoting said shoes into and out of contact with said tubular members.

10. A current reversing unit as called for in claim 'S including a solenoid operativelyv connected with earch shoe for pivoting the shoes into and out of contact with the tubular members.

Y 1l. A current reversing unit as called for in claim l@ including a resiliently yieldable connection between each solenoid and its shoe.

12. A current reversing unit comprising a frame structure, insulating support members on said frame structure, a pair electrically conducting tubular members of cylindrical shape mounted on said support members, two pair of contact shoes each insulatively supported on said frame structure for pivotal movement into and out of contact with the outer cylindrical surface of said tubular members, one shoe of each pair being adapted to contact one of the tubular members andthe other shoe in each pair being adapted to contact the other tubular member, a pair of input terminals adapted to be connected to a source of direct current, said terminals being insulatively mounted on said frame structure, said input terminals being electrically connected one with each of said tubular members, a pair of output terminals insulatively mounted on said frame structure, one of said output terminals being electrically connected to each shoe of one pair and the other output terminal being electrically connected to each shoe of the other pair and means for alternately and periodically pivoting one shoe in each pair into Contact with its respective tubular member and then the other shoe in each pair whereby the polarity at said output terminals is periodically reversed.

13. A current reversing unit as called for in claim 12 wherein said last mentioned means includes a solenoid for each contact shoe insulatively mounted on said frame structure, the movable element of each solenoid having d3 an insulated operative connection with its respective shoe.

14. A vcurrent reversing unit as called for in claim 13 wherein the contact shoes and their respective solenoids are disposed generally on diametrically opposite sides of the tubular members.

15. A current reversing unit as called for in claim 14 wherein said contact shoes are pivotally supported on said frame structure at one end thereof and the solenoids are operatively connected with the other ends of said contact shoes.

16. A current reversing unit as called for in claim 15 wherein said operative connection includes a link pivotally connected to the free end of each contact shoe and a spring connecting each link with the movable element of its respective solenoid,

.17. A device as called for in claim 6 wherein said contact members are each pivotally supported at one end and have a linkage connection with said solenoids at their opposite ends, said linkage connection including a spring operative when the solenoid is energized to bias the contact member into contact with its respective conductor.

BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner. 

7. AN ELECTRO-MECHANICAL CURRENT REVERSING UNIT COMPRISING A SUPPORT, A PAIR OF ELECTRICALLY CONDUCTING TUBULAR MEMBERS ON SAID SUPPORT, A FIRST PAIR OF CONTACT SHOES PIVOTALLY MOUNTED ON SAID SUPPORT AND ADAPTED TO PIVOT INTO AND OUT OF CONTACT ONE WITH EACH OF SAID TUBULAR MEMBERS, A SECOND PAIR OF CONTACT SHOES PIVOTALLY MOUNTED ON SAID SUPPORT AND ADAPTED TO PIVOT INTO AND OUT OF ENGAGEMENT ONE WITH EACH OF SAID TUBULAR MEMBERS, A PAIR OF INPUT TERMINAL CONNECTED ONE WITH EACH OF SAID TUBULAR MEMBERS, SAID INPUT TERMINALS BEING ADAPTED TO BE CONNECTED TO A SOURCE OF DIRECT CURRENT, A PAIR OF OUTPUT TERMINALS, THE CONTACT MEMBERS, IN ONE OF SAID CONTACT BEING CONNECTED TO ONE OUTPUT TERMINAL AND THE CONTACT MEMBERS IN THE OTHER PAIR BEING CONNECTED TO THE OTHER OUTPUT TERMINALS WHEREBY THE ALTERNATE CLOSING OF SAID TWO PAIRS OF CONTACTS REVERSE THE POLARITY AT SAID OUTPUT TERMINALS. 